Cardiovascular System Flashcards
The information from this deck should be pulled from: Netter's Physiology USMLE Review Book BRE review Book Lecture MNTS from 2016
Pulmonary hypertension
Right ventricular hypertrophy occurs in response to heightened pressure in the lungs
Aortic stenosis
Narrowing of the aortic valve that results in left ventricle hypertrophy
Mitral incompetence
Left atrial dilation may develop as a result of the elevation of left atrial pressure and volume caused by mitral regurgitation
What is the pulmonary arterial pressure?
25/10 (mean pressure 15)
What aortic pressure?
120/80 (mean pressure 95)
What is the volume distribution in the blood of the body?
64% veins 9% lungs 8% small arteries & arterioles 7% large arteries 7% heart in diastole 5% capillaries
What is the distribution of vascular resistance?
47% arterioles 27% capillaries 19% large arteries 7% veins
What is the distribution of blood flow in the body?
24% liver and GI 21% skeletal muscle 20% kidney 18% skin and other organs 13% brain 4% heart
What is VO2 distribution of blood flow in the body?
27% skeletal 23% liver and GI 21% brain 11% skin and other organs 11% heart 7% kidney
What is the resting membrane potential of the SA node?
-60mV
What is a normal rate of the SA node?
70 bpm
What are the phases of the action potentials of myocytes and His-Purkinje fiber?
Phase 4 (resting membrane potential): Close to the Nernst potential for K because of the efflux of K. Ion levels are restored by the Na/K pump, the Na/Ca exchanger, and the ATP-dependent Ca pump. Phase 0 (upstroke of the action potential): When cells reach threshold, Na ion gated channels open coupled with reduced conductance of K current. This depolarizes the cell. Phase 1 (rapid repolarization to the plateau): Na channel are inactivated and voltage gated K channels are opened. Phase 2 (the plateau): Slow L type Ca channels and inward current of Ca moderates the effects of the outflow of K. Phase 3 (repolarization): Gradual inactivation of the L-type Ca channels leads to activation of K channels causing rapid depolarization.
Effective refractory period
Phase 1 to much of phase 3, during which an AP cannot be generated
Relative refractory period
Until membrane potential is restored, an AP can be generated but it is more difficult
Chronotropic
effects heart rate
Dromotropic
effects conduction velocity
Inotropic
effects myocardial contractility
What effect does the sympathetic nervous system have on chromotoropic, dromotropic, and inotropics?
Increases them
What effect does the parasympathetic nervous system have on chromotoropic, dromotropic, and inotropics
Decreases them
P wave
atrial depolarization
QRS complex
ventricular depolarization
T wave
ventricular repolarization
Bradycardia
resting heart rate below 60 bpm
Tachycardia
resting heart rate above 100 bpm








